[BRCA1 and BRCA2 - pathologists starting kit].

Dysfunction of tumor suppressor genes BRCA1 and BRCA2 is involved in the pathogenesis of malignant tumors, especially breast and ovarian carcinoma. BRCA1/2 genes may be inactivated by germinal and somatic mutations or epigenetic changes. Germinal mutations are responsible for the hereditary breast and ovarian carcinoma syndrome. Defects of BRCA1/2 genes lead to the failure of homologous recombination, the basic mechanism for DNA double strand break repair. The resultant genomic instability is associated with a high risk of malignant transformation of the cell, but it also results in a higher sensitivity of tumors to platinum-based chemotherapeutic compounds which damage DNA structure directly. Inhibitors of poly(ADP-ribose) polymerase (PARP) are the next generation of antitumor agents aimed on the suppression of DNA single strand break repair. In homologous recombination deficient tumors, PARP inhibitors lead to accumulation of DNA damage and death of neoplastic cells through the mechanism of synthetic lethality. Platinum-based agents and PARP inhibitors are effective not only against tumors with germinal and somatic BRCA1/2 mutations but also against sporadic carcinomas with epigenetic BRCA1/2 inactivation or with defects of other independent genes involved in the control of homologous recombination. This phenomenon is represented by the term "BRCAness". Mutational analysis is used for the assessment of BRCA1/2 status, but it is complicated by the prominent length of BRCA1/2 genes and a wide spectrum of possible genetic alterations. Therefore, next generation sequencing seems to represent an optimal approach for BRCA1/2 evaluation nowadays. Development of reliable diagnostic tests for BRCAness in sporadic tumors and efforts to reverse platinum and PARP inhibitors resistance represent the key objectives of the forthcoming research.